Total depth after etching is 11.619 um
Calculated remaining resist as 7.69um, indicating an erosion of 1.05um in 10 minutes of etching
This equates to an erosion rate of 105 nm/min
The etch depth of 3.93um in 10 mins indicates an etch rate of 393.0nm/min
The selectivity is therefore 3.74:1